An Introduction to Data Analysis, Statistics, and Graphing

Transcription

1 An Introduction to Data Analysis, Statistics, and Graphing

2 What is a Graph? Present processes, relationships, and changes in a visual format that is easily understandable Attempts to engage viewers by simplifying the presentation of complex information Extremely useful in highlighting important points can be used to track trends and comparisons

3 Types of Graphs Different graphs serve different functions Can use various types to represent the data we have and need to present Including: Line Graphs Bar Graphs Circle/Pie Charts

4 KEY FEATURES OF GRAPHS Title: offers a short explanation of what your graph displays can be creative or straight forward Legend: informs the reader on what each piece displayed represents often, display multiple entries of information Source: explains where you found the information contained within your graph remember to give credit where and when it is due

5 What is Data Analysis? Let the statistics speak for themselves We facilitate this process through: organizing, manipulating, displaying and summarizing or synthesizing the numbers Additionally, we use this information as a basis from which to ask our questions and guide our analysis

6 Concepts and Terms Data sets contain information about individuals, which is organized in variables Individuals= objects described by a data set Variable= any characteristic of an individual; different individuals can have different values 2 Types of Variables: 1)Categorical= place individuals into categories (ex: gender, grade level, etc) 2)Quantitative= take numerical values for which we do arithmetic (ex: GPA, height, etc)

7 Exploring the Data WHO? What individuals do the data describe? How many are included? WHAT? How many variables do the data contain? What do these variables define or represent? In what units of measurement is each recorded in? WHY? What purpose do the data have? Are the variables suitable for the intended purpose?

8 Bar Graphs Can be used to show how something changes over time or to compare different times Represent time series data Consist of rectangular bars that differ in height or length according to their value or frequency of occurrence Display change in magnitude; and not a change in direction

9 Example of a Bar Graph

10 Benefits of using Bar Graphs Bar graphs can be very useful for: 1) Plotting data that span lengths of time (i.e. days, weeks, years) 2) Displaying really big changes across time (e.g. magnitude) 3)Comparing different items in a related category (i.e. differences between states)

11 Line Graphs One of the most popular graphs used to show change over time Used to display the comparison between variables, plotted on the horizontal x and vertical y axes X axis= measures of time Y axis= percentage or measures of quantity Commonly used as time series graphs that shows differences in direction

12 Example of Line Graph

13 Benefits of using Line Graphs Allows for the simultaneous presentation of multiple groups of data Good for plotting data that has peaks and valleys or was collected over a short period of time Forecast the future trends and results of data that has not yet been collected

14 Circle/Pie Charts Use divided segments/categories to represent the proportion of the variables, in relation to the whole Percentages are used to compare the segments, with the whole equaling 100% Represent and measure percentages at a set point in time do not show changes over time

15 Example of a Circle/Pie Chart

16 Pros and Cons of Circle/Pie Charts PRO s: Popular; easy to read and make Offer a great way to show how things break down by percentages CON s: Can be messy and difficult to read and understand Similar category values can lead to trouble in interpretation

17 A Hint Bar Graphs: to show large changes over time Line Graphs: better to use when smaller changes exist compare changes over the same period of time for multiple groups Circle/Pie Charts: when attempting to compare parts of a whole